This invention relates to an automotive carrier type conveying apparatus used in a self-propelled assembly line and more specifically to a conveying apparatus in which a conveying carrier having a load such as a car body or the like placed thereon moves itself along a conveying passage.
A conveying apparatus of this kind has been known heretofore from the Japanese Unexamined Patent Application Publication Tokkaisho No. 48-59511. A pit is formed of a wide channel-shaped track frame whose width extends across the entire width of a conveying passage and which is buried in the passage. A pair of running rails are securely laid on both side walls of the track frame and a guide rail is securely laid along the central portion of the bottom surface of the track frame. A steering frame is pivotally supported on the underside surface of the carrier body of a conveying carrier via a vertical steering shaft. Wheels that roll on along the running rails are pivotally supported on both left and right ends of the steering frame. A pair of front and rear guide rollers adapted to abut against one side surface of the guide rail are also pivotally supported on the steering frame. A swingable frame is provided on the carrier body which is swingable in a lateral direction. The swingable frame is provided with a driving roller abutting on the other side surface of the guide rail. A driving motor for driving the driving roller and the swingable frame are further urged by a spring so that the driving roller is pressed against the guide rail.
In the above-described conventional apparatus, the conveying carrier moves itself along the conveying passage as the driving roller rotates and, at the curved portions of the conveying passage, a reaction force of the pressure contact against the guide rail of the driving roller causes the steering frame to turn so as to have the pair of the guide rollers abut on the guide rail alike, whereby the wheels are changed in their moving direction for steering the conveying carrier at the curved portions.
In the foregoing apparatus, the pit is formed to extend across the entire width of the conveying passage. Therefore, the conveying passage can not be utilized additionally as a working space. Further, since it is arranged to receive load at the wheel attached to the steering frame, resistance to turning of the steering frame is increased to adversely affect the smooth steering operation thereof. It also requires, in addition to the steering frame, a swingable frame with a driving roller attached to the carrier body, thus resulting in a more complex structural arrangement which is a disadvantage.
In view of the foregoing, the present invention has for its object to provide a conveying apparatus of simplified structure in which a conveying passage is formed flat so as to be concurrently utilized as a working space and in which steerability of a conveying carrier is improved.